An internal combustion engine mounted upon an automobile, for example, is provided with an exhaust port to which an exhaust manifold is connected. The exhaust gases discharged from the combustion chamber of the internal combustion engine generally include unburned components. A catalyst member formed by laminating a suitable catalyst upon a ceramic carrier having a honeycomb shape is attached to the manifold. The exhaust gases flow into the manifold and, while flowing there-through, the exhaust gases are subjected to an oxidation reaction as a result of being disposed in contact with the catalyst member whereby the unburned components within the exhaust gases are cleaned or effectively removed therefrom.
In connection with an internal combustion engine having a small size and mounted upon a vehicle such as, for example, a motorcycle, an exhaust pipe is connected to the exhaust port of the engine, and a catalyst member having a honeycomb composition or structure, for example, and formed by laminating or adhering catalyst upon a cloth material such as, for example, glass wool, is disposed upon an inner surface of the exhaust pipe by utilizing a press plate, for example. The unburned components of the exhaust gases discharged from the combustion chamber of the engine are therefore forced into contact with the catalyst member whereby the unburned components of the exhaust gases are effectively cleaned or removed from the exhaust gases through means of the aforenoted oxidation reaction. These conventional techniques are disclosed within, for example, Japanese Patent Publication No. 59-1324 and Japanese Patent Laid-open Publication No. 61-96120.
However, with respect to the catalyst having a honeycomb structure since the exhaust gases pass through a plurality of perforations formed within the honeycomb catalyst member, the flow region for the exhaust gases is reduced and the exhaust gas flow is influenced by means of the resistance defined by means or characteristic of the catalyst member having the honeycomb structure. This fact results in the lowering of the output of the engine and, particularly, with respect to a small sized engine, the lowering of the output adversely affects the engine performance. Moreover, the location of such honeycomb catalyst member within the manifold enlarges the total size of the manifold, such being undesirable in connection with the construction and the manufacturing costs thereof. Furthermore, the adherence of the catalyst member made of cloth material to the inner surface of the exhaust pipe involves the problem of the adherence thereof as well as increased costs in addition to the problem of performance or durability of the engine itself.